In animals, including humans, mothers supply eggs with the mRNAs and proteins that drive the critical early stages of development. These maternally supplied factors directly control early developmental processes, and establish trajectories for the rest of development. Altering the levels of maternally deposited factors in model organisms in the laboratory can have dramatic effects on development, and hence adult phenotypes. Despite the importance of these maternally supplied factors to the development and fitness of the organism, little is known about how they evolve. This is of particular interest, because genetic control over this period of development has to be coordinated across two different genomes, that of the mother and that of the zygote, a form of epistasis which may pose a particular challenge to evolution. The fly species in the genus Drosophila, with its rich diversity of species covering 50 million years of divergence time, provide a great model for such a study. The Drosophila system has the advantage of extensive catalogs of the mRNAs and proteins deposited by females of the model species D. melanogaster, and much research has gone into understanding the specific developmental and regulatory roles of many of these factors. Despite the extent of the previous work in D. melanogaster, we know very little about how these maternally derived factors vary across species. This work proposes to: 1) characterize the mRNA pools in embryos, both those deposited by the mother and those later transcribed by the zygote, within and between Drosophila species, using mRNA sequencing methods, 2) determine phylogenetic patterns and life-history correlates of maternal and zygotic mRNA pool changes, and 3) identify genetic mechanisms underlying the evolutionary turnover of mRNA pools within and between species. The goal of this project is to understand how these mRNA pools evolve, and what the effect of these changes will be on the developmental process and the fitness of the organism.